topic Re: Tele extenders in Gear Guide

Which tele extender should I buy? 1.4x vs 2x, series II vs series III

FredSchall — Fri, 31 Oct 2025 17:45:47 GMT

I would like to purchase a Canon tele extender. Do I want a 1.4x or 2x and do I want series II or series III. Advantages, disadvantages? Thoughts? No big deal on series? Thanks

Re: Tele extenders

jrhoffman75 — Sat, 22 Jan 2022 20:06:19 GMT

What lenses do you have?

The Mark III versions are optimized for the latest versions of the super-teles.

Discussion about 1.4X III: Canon EF 1.4x III Extender Review (the-digital-picture.com)

Discussion about 2.0X III: Canon EF 2x III Extender Review (the-digital-picture.com)

Re: Tele extenders

Waddizzle — Sat, 22 Jan 2022 21:21:12 GMT

What camera body are you looking use with the teleconverters? The teleconverters are not compatible with any lens. Check your camera’s User Guide for “lens groups”. The 90D has a “Supplementary Information” User Guide that contains the “lens groups” info.

Re: Tele extenders

ebiggs1 — Sun, 23 Jan 2022 17:16:36 GMT

Before you decide on which to get you need to know if it can even be used with your lenses. IMHO, never buy a 2x tel-con but I don't like and use any tel-con. There is always a great debate as to whether it is better to use a converter or simply crop more in post. You may find you are just as well off in post and save yourself some money.

Re: Tele extenders

ebiggs1 — Sun, 23 Jan 2022 17:36:31 GMT

Addendum.

The downside is you lose IQ. You lose a stop or two depending on which converter you select. Your AF speed will slow and you may lose AF altogether or have just one AF point.

There are two lenses that do work well with a 1.4x tel-con. Never the 2x however. The ef 70-200mm f2.8L and the ef 300mm f4l IS. The nice thing about the 300mil is it has the IQ to give up, but it becomes a 4200mm f5.6 lens with IS. Canon's fantastic and unique ef 400mm f5.6L does not have IS. So the converted 300mil is a good give and take.

The ef 70-200mm f2.8L just works all way around with a 1.4x.

Re: Tele extenders

FredSchall — Sun, 23 Jan 2022 19:33:55 GMT

Thanks. 100-400 ef usm II.

Re: Tele extenders

FredSchall — Sun, 23 Jan 2022 19:43:31 GMT

100-400 ef usm II. It will work. Thanks.

Re: Tele extenders

FredSchall — Sun, 23 Jan 2022 19:45:42 GMT

How about the 1.4 on a 100-400 ef usm II. ??

Re: Tele extenders

jrhoffman75 — Sun, 23 Jan 2022 19:57:50 GMT

It will depend on your end use.
I have a 1D X Mark III and I print 13x19 as my largest output.
I ran an informal test with the 100-400 Mk II lens with the 1.4X III compared to cropping to equivalent framing in Lightroom.
I used a lens test image to be more challenging compared to a random shoot image.
i could see no difference between the two images.
Try cropping some of your images and see how they stand up.

Re: Tele extenders

Waddizzle — Sun, 23 Jan 2022 20:49:55 GMT

I guess this means that you’re using a 90D.

Okay, the 90D Lens Groups schedules suggest that an EF 1.4x III “will work” with the EF 100-400mm f/4,5-5,6L IS II USM. But, how well it “will work” actually work? Let’s look at what we know will happen.

You will lose a full stop of light on exposure because the effective maximum aperture is reduced by a full stop. Your total number of available AF points will be reduced to 27, because the reduced maximum aperture reduces the amount of light reaching the AF sensor.

A reduced amount of light reaching the AF sensor almost always means reduced AF speed as a result. In the case of the 90D, I would only use the center AF point with the 1.4x teleconverter.

I feel this is why using a TC reduces image quality. It isn’t the extra glass as much as it is probably the compromises imposed on the AF system. Some of this can be overcome by exceptions written into the camera firmware, but I doubt if this is the case for a 90D.

Re: Tele extenders

ebiggs1 — Sun, 23 Jan 2022 21:01:19 GMT

"How about the 1.4 on a 100-400 ef usm II. ??"

I wouldn't do it personally but some guys tell me it works fairly well. Also John's advice, which I totally agree with, is using a top of the line camera. When you start adding a tel-con that makes s huge difference. I don't remember what camera, perhaps you said, that you are using this on.

I would go the crop route first before you spend your money. You may be well satisfied. Go d/l DPP4 and try it.

Re: Tele extenders

wq9nsc — Sun, 23 Jan 2022 23:19:09 GMT

Fred, the answer also depends on your intended use. Any extender will somewhat reduce autofocus performance, it isn't just the extender adding to the overhead of the AF algorithm but also the fact that you are losing one or two stops of light which reduces AF speed due to reduced performance of the AF sensor in lower light. So it is more of a problem for action shots like sports or wildlife. AF on the better bodies will still work quite well but not as well as they do without the extender so it is one of the compromises you have to consider.

I have a couple of flavors of the Canon 1.4X (versions II and III) and both work pretty well with my EF 70-200 f2.8 and fast telephoto primes. I usually keep the 1.4X in a bag with me in case some unexpected need comes up but the only times I have used it in the last few years was for a few baseball games combined with the 400 f2.8 when shooting batters from behind the outfield fence and with my 800 f5.6 when shooting eagles and that combination requires a lot of collaboration between the camera and user to have the subject in focus at the exact point and time needed.

I also have a Canon 2X and although it can produce decent images with the EF 300 and EF 400 f2.8 glass, the images are clearly impaired compared to what these extremely sharp lenses can produce by themselves. The results with a 2X will be far worse on lesser glass and I would avoid the 2X. Also, a lot of camera body/lens combinations won't autofocus with a 2X extender.

Realistically, if you feel you are going to be using the extender for a very large percentage of your photos then you need to compare the extender/lens combination to the results from one of the 150-600 setups.

Rodger

Re: Tele extenders

FredSchall — Mon, 24 Jan 2022 04:32:28 GMT

Thank you so much for you terrific and very thorough explanation. I really appreciate it.

Take care. Fred

Re: Tele extenders

FredSchall — Mon, 24 Jan 2022 04:41:19 GMT

Thank you so much for your terrific and very thorough explanation. I really appreciate it.

Take care. Fred

Re: Tele extenders

regr — Wed, 29 Oct 2025 16:44:26 GMT

Hello guys, I have used a 1.4x on my EF 100-400mm L mk 1 lens for years. both with my 5D mk II, 1DSmkIII and 1DX. I have had very good results with it even when cropping some, I will attach a few samples for you guys. Very powerful small combo. You will loose all but the centre 5 focus points work fine with this and still AF works very well.